DB too bloated (1.7G) to even scan – What to do?

So, I somehow ended up with a 1.7GB _options table (no, I have no idea how).

I tried all the automatic options, but it seems that I need to deepscan the table before doing any meaningful debloating… however the table is so large that selecting the Options tab just does not work: I get a lot of scary error messages, and I’m back to square one.

Any suggestions on how to go about this? (Bonus points if you keep in mind I am not too software-literate. Please explain it like I’m 5!)